Method of attaching heels to shoes

Abstract

A plastic heel is attached by inserting through an insole of a shoe a fastener, and vibrating the fastener at ultrasonic frequency to cause its shank to melt the plastic and become embedded in the heel. The fastener may be a staple with wide legs having holes therein. The shank of the shoe may be bridged by the staple for added attachment strength. Since less work penetration is needed than in nail-attaching of heels, advantage is gained especially in securing sharply tapering or so-called "stiletto" heels.

Having thus described my invention, what I claim as new and desire to secure as Letters Patent of the United States is: 
     
       1. A method of attaching a thermoplastic heel to a shoe having an insole by means of a fastener having a head portion and a shank portion, the method comprising positioning the heel against the heel seat portion of the shoe, inserting the shank portion through the insole and into the thermoplastic material of the heel with the head portion overlying the insole, vibrating the fastener at an ultrasonic frequency to at least soften the material of the heel adjacent to the shank portion, and pressing the fastener into the heel to embed the shank portion in the material while it is at least softened said fastener having its shank portion formed with at least one hole extending transversely therethrough into which the softened heel material flows. 
     
     
       2. The method of claim 1 wherein the fastener is at least one staple. 
     
     
       3. The method of claim 1 wherein the vibration of the fastener is approximately at a frequency of 20 kiloHertz and an amplitude of about 25 microns. 
     
     
       4. The method of claim 1 wherein the vibration of the fastener also facilitates its penetration through the insole. 
     
     
       5. The method of claim 1 wherein the fastener is formed U-shape from a metal strip and its shank portion includes a pair of tapering wide legs spaced to straddle a shank of the shoe when driven into the thermoplastic material. 
     
     
       6. The method of claim 5 wherein each leg has at least one hole formed therein for receiving the melted or softened thermoplastic material. 
     
     
       7. The method of claim 1 wherein the fastener is of staple-shape and the head thereof is slightly concave to bridge the shoe shank and correspond to the heel of a wearer of the shoe. 
     
     
       8. The method of claim 7 wherein the fastener is formed of a metal strip and has a pair of tapering legs each of which has at least one transverse hole therein disposed to receive thermoplastic when embedded in the heel.